This AC WORKS™ brand locking adapter [NEMA L5-30P], is a very durable molded adapter. This locking adapter is a NEMA L5-30P to NEMA L14-30R. The NEMA L5-30P is a 30 Amp, 125 Volt, 3-prong male plug. The NEMA L14-30R is a 30 Amp, 125/250 Volt, 4-prong female connector. It features nickel-plated terminals and plugs to prevent copper rusting and has a maximum operating power of 3750W.